Hi,
Already have Isonic 94 2010 wich I ride with a 6.5 Severne Overdrive sail.
Would like to have new Isonic 117 or 127 with new Neil Pryde H2 sails 7.2 or 7.7 or TR9 or similar, witch I think should work well in 10 to 17 Kn of wind on small freswater lake, for a very efficient small gabarit of 5'-6" and 140 pounds. What do you think? What is your choice??

At your weight and sails you use the iSonic 107 or 110 will be the best choice in sea water, for fresh water I will recommend the 110. The 117 will be perfect with 7.8 to 9.2 while the 110 will be perect for 7.0 to 8.6.

Over a 1 year usage, I rode combo (a) only 3x because 18 knots of wind and its associated chop are the upper limit that I can handle with such a wide board for my light weight. Chop is becoming the limiting factor when going fast (29+ kts Vmax) on such a wide board for my 65 kg (no problem at all on a much narrower iSonic 53 speed in same condition). I'm simply too light to keep the nose down and not flying up in the air after the 4th or 5th chop hop. I simply cannot imagine myself riding that wide beast in 20+ knots of wind with a 7.2 sail...

Last year, the combo (b) has been riden one third of total TOW while combo (c) has been riden 2 third of total TOW. This is the perfect light wind (7-15 knots) combo for me with 2 sails and 4 fins.

So, if the wind in your area blows most of the time around 10 knots, better take an iSonic 117 + 8.6 sail. If it blows most of the time 14 ± 4 knots, I guess an iSonic 110 + 7.8 sail combo should be plenty large enough.

I am 72 kilos and have the iSonic 110 with a H2 8.2 and a SCS 7.0. The board is a lightwind machine for me. It takes a little technique to get it going in the lightest gust, but once up planing it goes through lulls with ease. The speed makes me often believe there is enough wind to plane through every jibe and in the lightest wind I always get surprised about how light the wind is when I turn right down wind and come to a stop. A little more wind and the board screams through the jibes full planing with ease.
With the 7.0 the board feels like a speed board. I am amazed how good it works being so big.
At 140 pounds I can not think that you need anything bigger than a 110.

Only thing is that I do not sail in fresh waters, but I weight almost 20 pounds more than you.